cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-10 of 13 results. Next

A006335 a(n) = 4^n*(3*n)!/((n+1)!*(2*n+1)!).

Original entry on oeis.org

1, 2, 16, 192, 2816, 46592, 835584, 15876096, 315031552, 6466437120, 136383037440, 2941129850880, 64614360416256, 1442028424527872, 32619677465182208, 746569714888605696, 17262927525017812992, 402801642250415636480, 9474719710174783733760, 224477974671833337692160
Offset: 0

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Author

Keywords

Comments

Number of planar lattice walks of length 3n starting and ending at (0,0), remaining in the first quadrant and using only NE,W,S steps.
Equals row sums of triangle A140136. - Michel Marcus, Nov 16 2014
Number of linear extensions of the poset V x [n], where V is the 3-element poset with one least element and two incomparable elements: see Kreweras and Niederhausen (1981) and Hopkins and Rubey (2020) references. - Noam Zeilberger, May 28 2020

Examples

			G.f. = 1 + 2*x + 16*x^2 + 192*x^3 + 2816*x^4+ 46592*x^5 + 835584*x^6 + ...
		

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Equals 2^(n-1) * A000309(n-1) for n>1.
Cf. A098272. First row of array A098273.

Programs

  • Magma
    [4^n*Factorial(3*n)/(Factorial(n+1)*Factorial(2*n+1)) : n in [0..20]]; // Wesley Ivan Hurt, Nov 16 2014
    
  • Maple
    A006335:=n->4^n*(3*n)!/((n+1)!*(2*n+1)!): seq(A006335(n), n=0..20); # Wesley Ivan Hurt, Nov 16 2014
  • Mathematica
    aux[i_Integer, j_Integer, n_Integer] := Which[Min[i, j, n] < 0 || Max[i, j] > n, 0, n == 0, KroneckerDelta[i, j, n], True, aux[i, j, n] = aux[-1 + i, j, -1 + n] + aux[i, -1 + j, -1 + n] + aux[1 + i, 1 + j, -1 + n]]; Table[aux[0, 0, 3 n], {n, 0, 25}] (* Manuel Kauers, Nov 18 2008 *)
    Table[(4^n (3 n)! / ((n + 1)! (2 n + 1)!)), {n, 0, 200}] (* Vincenzo Librandi, Nov 17 2014 *)
  • PARI
    {a(n) = if( n<0, 0, 4^n * (3*n)! / ((n+1)! * (2*n+1)!))}; /* Michael Somos, Jan 23 2003 */
    
  • Sage
    def a(n):
        return (4**n * binomial(3 * n, 2 * n)) // ((n + 1) * (2 * n + 1))
    # F. Chapoton, Jun 01 2020

Formula

G.f.: (1/(12*x)) * (hypergeom([ -2/3, -1/3],[1/2],27*x)-1). - Mark van Hoeij, Nov 02 2009
a(n+1) = 6*(3*n+2)*(3*n+1)*a(n)/((2+n)*(2*n+3)). - Robert Israel, Nov 17 2014
a(n) ~ 3^(3*n + 1/2) / (4*sqrt(Pi)*n^(5/2)). - Vaclav Kotesovec, Mar 26 2016
E.g.f.: 2F2(1/3,2/3; 3/2,2; 27*x). - Ilya Gutkovskiy, Jan 25 2017

Extensions

Edited by N. J. A. Sloane, Dec 20 2008 at the suggestion of R. J. Mathar

A214801 Number of solid standard Young tableaux of shape [[2*n,n],[n]].

Original entry on oeis.org

1, 6, 174, 7020, 325590, 16290708, 854630476, 46305862488, 2568272967270, 144984584562180, 8298621602461476, 480298712286979560, 28052543639835133692, 1650956086756046986440, 97790578929910135588440, 5824509559447044190027952, 348581174512709008160833158
Offset: 0

Views

Author

Alois P. Heinz, Jul 28 2012

Keywords

Crossrefs

Central row elements of A214775.
Column k=2 of A176129.

Programs

  • Maple
    b:= proc(x, y, z) option remember; `if`(z>y, b(x, z, y),
          `if`({x, y, z}={0}, 1, `if`(x>y and x>z, b(x-1, y, z), 0)+
          `if`(y>0, b(x, y-1, z), 0)+ `if`(z>0, b(x, y, z-1), 0)))
        end:
    a:= n-> b(2*n, n, n):
    seq(a(n), n=0..20);
  • Mathematica
    b[x_, y_, z_] := b[x, y, z] = If[z>y, b[x, z, y], If[Union[{x, y, z}] == {0}, 1, If[x>y && x>z, b[x-1, y, z], 0] + If[y>0, b[x, y-1, z], 0] + If[z>0, b[x, y, z-1], 0]]]; a[n_] := b[2n, n, n]; Table[a[n], {n, 0, 16}] (* Jean-François Alcover, Feb 05 2015, after Alois P. Heinz *)

Formula

Recurrence: (n-1)*n^2*(2*n-1)*(2*n+1)*(4*n-1)*(4*n+1)*(392*n^4 - 2044*n^3 + 4216*n^2 - 3944*n + 1377)*a(n) = 2*(n-1)*(1859648*n^10 - 13670048*n^9 + 43255264*n^8 - 75152192*n^7 + 75863336*n^6 - 41825576*n^5 + 7317576*n^4 + 5067372*n^3 - 3441344*n^2 + 785094*n - 59535)*a(n-1) - 4*(2*n-3)*(4*n-7)*(4*n-5)*(1310848*n^8 - 7998592*n^7 + 19695952*n^6 - 24269488*n^5 + 15125236*n^4 - 3514192*n^3 - 1066614*n^2 + 533457*n - 45927)*a(n-2) + 5184*n*(2*n-5)*(2*n-3)*(4*n-11)*(4*n-9)*(4*n-7)*(4*n-5)*(392*n^4 - 476*n^3 + 436*n^2 - 76*n - 3)*a(n-3). - Vaclav Kotesovec, Aug 31 2014
a(n) ~ sqrt((5*sqrt(5)-11)/4) * 64^n / (Pi*n). - Vaclav Kotesovec, Aug 31 2014

A215686 Number of solid standard Young tableaux of shape [[3*n,n],[n]].

Original entry on oeis.org

1, 12, 690, 52808, 4558410, 420421056, 40433534960, 4002511248720, 404653074076602, 41573640435563720, 4325688482694408060, 454713687334494619200, 48204482093235945250800, 5146506898529612988887424, 552782991828545241240684480, 59682974236253934536767852960
Offset: 0

Views

Author

Alois P. Heinz, Aug 20 2012

Keywords

Crossrefs

Column k=3 of A176129.

Programs

  • Maple
    b:= proc(x, y, z) option remember; `if`(z>y, b(x, z, y), `if`(z>x, 0,
          `if`({x, y, z}={0}, 1, `if`(x>y and x>z, b(x-1, y, z), 0)+
          `if`(y>0, b(x, y-1, z), 0)+ `if`(z>0, b(x, y, z-1), 0))))
        end:
    a:= n-> b(3*n, n, n):
    seq(a(n), n=0..20);
  • Mathematica
    b[x_, y_, z_] := b[x, y, z] = If[z>y, b[x, z, y], If[Union[{x, y, z}] == {0}, 1, If[x>y && x>z, b[x-1, y, z], 0] + If[y>0, b[x, y-1, z], 0] + If[z>0, b[x, y, z-1], 0]]]; a[n_] := b[3n, n, n]; Table[a[n], {n, 0, 15}] (* Jean-François Alcover, Feb 05 2015, after Alois P. Heinz *)

Formula

Recurrence: 144*n^2*(2*n-1)^2*(3*n-1)*(3*n+1)*(6*n-1)*(6*n+1)*(1054762104*n^8 - 12255641802*n^7 + 61733195125*n^6 - 176088471031*n^5 + 310993546391*n^4 - 348002018003*n^3 + 240698328276*n^2 - 93950633268*n + 15815567520)*a(n) = 3*(16185096657265536*n^16 - 237611988564522912*n^15 + 1583108012261189688*n^14 - 6336788565970939206*n^13 + 16995962918085979601*n^12 - 32239020575894967680*n^11 + 44456039640264512829*n^10 - 45040072648450035120*n^9 + 33379794951068698383*n^8 - 17660683589724361536*n^7 + 6240753949747677391*n^6 - 1170756653568973234*n^5 - 67328664931986180*n^4 + 105177779152514568*n^3 - 28053879047153568*n^2 + 3460226308012800*n - 166227489792000)*a(n-1) - 5*(5*n-9)*(5*n-8)*(5*n-7)*(5*n-6)*(1065259096459008*n^12 - 11533800266013504*n^11 + 53860225549987304*n^10 - 142107589766231326*n^9 + 232900286313689643*n^8 - 245074012300774359*n^7 + 164357596249809711*n^6 - 65773579693921743*n^5 + 11793083348968270*n^4 + 1470831449279884*n^3 - 1161186153316104*n^2 + 208213965227520*n - 12225693916800)*a(n-2) + 97200*(5*n-14)*(5*n-13)*(5*n-12)*(5*n-11)*(5*n-9)*(5*n-8)*(5*n-7)*(5*n-6)*(1054762104*n^8 - 3817544970*n^7 + 5477041423*n^6 - 3991100299*n^5 + 1435002321*n^4 - 129425495*n^3 - 68369752*n^2 + 19574652*n - 1364688)*a(n-3). - Vaclav Kotesovec, Aug 31 2014
a(n) ~ sqrt(330*sqrt(33)-1770)/36 * 5^(5*n) / (Pi * n * 3^(3*n)). - Vaclav Kotesovec, Aug 31 2014

A246619 Number of solid standard Young tableaux of shape [[4*n,n],[n]].

Original entry on oeis.org

1, 20, 1876, 229680, 31497284, 4600393936, 699440711760, 109341854545792, 17445620031680100, 2827280025640259280, 463882742476664594512, 76875122571167921990080, 12845419277094419018993808, 2161338658294952555703260480, 365816910931667192749720139072
Offset: 0

Views

Author

Vaclav Kotesovec, Aug 31 2014

Keywords

Crossrefs

Cf. column k=4 of A176129.

Formula

a(n) ~ sqrt(4*sqrt(3)-6) * 3^(6*n+1) / (Pi * n * 2^(2*n+3)). - Vaclav Kotesovec, Aug 31 2014

A215123 Number of solid standard Young tableaux of shape [[n^2,n],[n]].

Original entry on oeis.org

1, 2, 174, 52808, 31497284, 31113230148, 46190668836656, 96484621769643360, 270280816277448460968, 979042561410295182717884, 4456728497956906393963534248, 24916868994347706845906490576432, 167903137478620963997932010166057408
Offset: 0

Views

Author

Alois P. Heinz, Aug 03 2012

Keywords

Crossrefs

Central row elements of A215122.
Main diagonal of A176129.

Programs

  • Maple
    b:= proc(x, y, z) option remember; `if`(zy and x>z, b(x-1, y, z), 0)+
          `if`(y>0, b(x, y-1, z), 0)+ `if`(z>0, b(x, y, z-1), 0)))
        end:
    a:= n-> b(n^2, n, n):
    seq(a(n), n=0..15);
  • Mathematica
    $RecursionLimit = 1000; b[x_, y_, z_] :=  b[x, y, z] = If[zy && x>z, b[x-1, y, z], 0] + If[y>0, b[x, y-1, z], 0] + If[z>0, b[x, y, z-1], 0]]]; a[n_] := b[n^2, n, n]; Table[a[n], {n, 0, 15}] (* Jean-François Alcover, Feb 05 2015, after Alois P. Heinz *)

Formula

a(n) ~ exp(2*n+2) * n^(2*n-1) / (2*Pi). - Vaclav Kotesovec, Jan 19 2015

A246620 Number of solid standard Young tableaux of shape [[5*n,n],[n]].

Original entry on oeis.org

1, 30, 4140, 738192, 146955276, 31113230148, 6851807953900, 1550766110966400, 358116337203378732, 83984165552626389864, 19937272615715693766528, 4779986445560522545646400, 1155414579663560935856564700, 281212253617692376239817669056
Offset: 0

Views

Author

Vaclav Kotesovec, Aug 31 2014

Keywords

Crossrefs

Cf. Column k=5 of A176129.

Formula

a(n) ~ sqrt(7/10*(13*sqrt(65)-83))/10 * 7^(7*n) / (Pi * n * 5^(5*n)). - Vaclav Kotesovec, Aug 31 2014

A215687 Number of solid standard Young tableaux of shape [[2*n,2],[2]].

Original entry on oeis.org

0, 16, 174, 690, 1876, 4140, 7986, 14014, 22920, 35496, 52630, 75306, 104604, 141700, 187866, 244470, 312976, 394944, 492030, 605986, 738660, 891996, 1068034, 1268910, 1496856, 1754200, 2043366, 2366874, 2727340, 3127476, 3570090, 4058086, 4594464, 5182320
Offset: 0

Views

Author

Alois P. Heinz, Aug 20 2012

Keywords

Crossrefs

Row n=2 of A176129.

Programs

  • Maple
    a:= n-> (-7+(7+(12+4*n)*n)*n)*n;
    seq(a(n), n=0..40);
  • Mathematica
    LinearRecurrence[{5,-10,10,-5,1},{0,16,174,690,1876},40] (* Harvey P. Dale, Jul 08 2017 *)

Formula

G.f.: 2*(3*x^3-10*x^2+47*x+8)*x/(1-x)^5.
a(n) = n*(2*n-1)*(2*n^2+7*n+7).

A215688 Number of solid standard Young tableaux of shape [[3*n,3],[3]].

Original entry on oeis.org

0, 192, 7020, 52808, 229680, 738192, 1950512, 4488180, 9314448, 17841200, 32050452, 54630432, 89126240, 140105088, 213336120, 315984812, 456821952, 646447200, 897527228, 1225048440, 1646584272, 2182577072, 2856634560, 3695840868, 4731082160, 5997386832
Offset: 0

Views

Author

Alois P. Heinz, Aug 20 2012

Keywords

Crossrefs

Row n=3 of A176129.

Programs

  • Maple
    a:= n-> `if`(n=0, 0, 32+(-312+(-362+(171+(657+(405+81*n)*n)*n)*n)*n)*n/4):
    seq(a(n), n=0..40);

Formula

G.f.: 4*(8*x^6-41*x^5+105*x^4+181*x^3+1925*x^2+1419*x+48)*x/(1-x)^7.
a(n) = (3*n-1)*(3*n-2)*(3*n^2+13*n+16)*(3*n^2+5*n+4)/4 for n>0, a(0) = 0.

A246621 Number of solid standard Young tableaux of shape [[6*n,n],[n]].

Original entry on oeis.org

1, 42, 7986, 1950512, 530931786, 153580152492, 46190668836656, 14274134610246720, 4500027052542851130, 1440557297650459814996, 466776334221187994469180, 152741149363060061495819904, 50388989722150284436348268528, 16737346518387797143628281698720
Offset: 0

Views

Author

Vaclav Kotesovec, Aug 31 2014

Keywords

Crossrefs

Cf. column k=6 of A176129.

Formula

a(n) ~ sqrt((7*sqrt(21)-23)/6)/3 * 8^(8*n) / (Pi * n * 6^(6*n)). - Vaclav Kotesovec, Aug 31 2014

A246632 Number of solid standard Young tableaux of shape [[7*n,n],[n]].

Original entry on oeis.org

1, 56, 14014, 4488180, 1600210950, 606021260768, 238569956361984, 96484621769643360, 39804374977976438550, 16673506088758905946560, 7069147910017295001150416, 3026650659542070433624365472, 1306409837754633649293171595680, 567753549048151735754482750312560
Offset: 0

Views

Author

Vaclav Kotesovec, Aug 31 2014

Keywords

Crossrefs

Cf. column k=7 of A176129.

Formula

a(n) ~ 3/14*sqrt(3/14*(5*sqrt(105)-33)) * 9^(9*n) / (Pi * n * 7^(7*n)). - Vaclav Kotesovec, Aug 31 2014
Showing 1-10 of 13 results. Next